I adopted an underweight chi and she will not eat her dog food. what should i do?

[Janene]

I have tried wet dog food, and her solid food mixed with water and heated in the microwave. I have tried mixing them together as well. She just will not eat dog food. She sometimes eats the wet food but not always. And she is very underweight so I can't just wait till she feels like eating it. She has to eat. I need some major help. I know its not that she's not hungry because she eats her treats still. I only give her treats because she needs to eat something at less.